As usual, Syria remains complicated. The fighting continues to shift.
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Assad/Syria/Russians are fully committed to the war in N Syria with Turkey. Iranian fighters and shia militants from Iraq are concentrated to that fight.
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That leaves S Syria/Hezbollah relatively wide open to Israeli air raids. And they are very effective. Iranian war materiel is being degraded as fast as it shows along with the trained operators.
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Iran’s failed economy is making it politically difficult to keep spending money in Syria. Iranians are largely turning away from that war.
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However, the Quds force has many independent sources of funding so that supply goes on.
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Iraqi, Iranian led militias are still heavily committed to fighting ISIS in W Iraq. Should ISIS be fully degraded, those fighters will likely shift to Syria. More importantly that will open up the rat lines into Syria so that Iranian war material can more stealthily get in country.
I don’t disagree with your statements.
Even so, I think everything is tending to degrade the long term importance of Assad. I think without the Sunni dominated “Syrian opposition” gaining anything, the various forces that are not Assad’s that are being backed by Iran and Russia will in time (????) be able to officially displace Assad, as a figurehead they will no longer need - they will be stronger than Assad, they will be Shia dominant and Assad will not have Sunni Syrians to call on for help. The beneficiaries of those forces reaching that state will be Iran and Russia. They will jointly arrange a replacement for Assad. He will go into exile.